
// 1. test add
// build: g++ -I/usr/include/eigen3 1.matrix_add.cpp
#include <iostream>
#include <Eigen/Dense>
using namespace std;
int main()
{
    Eigen::Matrix2d a;
    a << 1, 2,
        3, 4;
    Eigen::MatrixXd b(2, 2);
    b << 2, 3,
        1, 4;
    // 大小相同可以执行 加
    std::cout << "a + b =\n"
              << a + b << std::endl;
    std::cout << "a - b =\n"
              << a - b << std::endl;

    std::cout << "Doing a += b;" << std::endl;
    a += b;
    std::cout << "Now a =\n"
              << a << std::endl;

    // Vector 可以直接减
    Eigen::Vector3d v(1, 2, 3);
    Eigen::Vector3d w(1, 0, 0);
    std::cout << "-v + w - v =\n"
              << -v + w - v << std::endl;
}
